1. Field of the Invention
The present invention relates to point of contact test tools for testing integrated circuit chips, and more particularly to a test tool that includes an easily replaceable probe tip.
2. Related Art
As integrated circuit (IC) devices become smaller and more densely populated, performing electrical point of contact testing becomes increasingly more difficult. As the number of circuits on a device increases, the number of required tests also increases. Thus, there is an ongoing need to develop test equipment that can operate at higher and higher rates of speed. Moreover, as the circuits become smaller and smaller, the precision required by the test equipment likewise increases. In order to achieve high speed precision in point of contact testing, specialized automated devices have been developed. Such patented devices include IBM""s Hummingbird Mini-positioner (U.S. Pat. No. 5,180,955) and IBM""s Probe positioning Actuator (U.S. Pat. No. 5,153,472).
The Hummingbird Mini-positioner uses single or double cantilever beam probes to perform electrical tests. These probes are screwed in place onto an actuator which moves up and down along the z-axis to contact a point beneath the probe. The actuator is also positionable along the x and y axises in order to contact various points on the device being tested. Test equipment, such as the Hummingbird Mini-positioner can perform over 100 tests per second with an accuracy in the range of five microns.
Unfortunately, due the demand placed on such test equipment, the delicate probes wear out often and must be changed regularly. Because the probe tips are so small, typically less than 2.5 millimeters, and the screw that holds the probe assembly in place is even smaller, typically 0.5 millimeters, it is extremely tedious and time consuming to change the very tiny screw that holds the assembly in place. The probes and screws are so small that when dropped they are virtually lost. More importantly, the screws can be sucked into the test equipment body by any magnets that reside within the equipment, causing expensive mechanical damage.
Therefore, without a better way of changing probe tips in precision point of contact test equipment, the time and costs involved in testing IC devices will be increased. All of the aforementioned prior art is hereby included by reference.
The present invention provides an improved probe housing that eliminates existing screw mounted systems. The invention allows a cantilever beam assembly to be slid into a dovetail housing and locked into place. Locking is accomplished using a quick release system that provides a releasable force onto the cantilever beam. The force is provided with a cantilever spring in a first embodiment and with a non-removable cam device (e.g., a non-removable screw system) in a second embodiment.
The improvement simplifies the changing of probe tips and reduces the possibility of tiny screws being sucked into the body of the test equipment. Moreover, the invention lends itself to the automated changing of probe tips, which would be highly desirable in a high production environment where high wear of probe tips is experienced.